U.S. stocks fell on Tuesday, dragged down by healthcare companies and Alcoa, which kicked off the earnings season on a disappointing note.

The S&P 500 healthcare .SPXHC sector dropped 0.71 percent as Illumina’s (ILMN.O) disappointing results weighed. The company’s stock lost more than a quarter of its value after the diagnostic test maker cut its third-quarter revenue forecast for the second time in a row.

Alcoa (AA.N), which unofficially signals the start of the earnings period, reported revenue and profit that fell short of market expectations.

The aluminum producer’s stock fell 7.7 percent on Tuesday morning.

“Earnings will begin to resolve the recent choppiness and uncertainty in the market, pushing investors one way or another,” said Andre Bakhos, managing director at Janlyn Capital in Bernardsville, New Jersey.

Overall earnings of S&P 500 companies are expected to fall by 0.7 percent in the third quarter, according to Thomson Reuters data.

Oil prices fell 0.9 percent, a day after hitting a one-year high, as investors questioned whether a deal to cut output would be enough to rebalance the market by next year. [O/R]

The dollar .DXY rose 0.53 percent, marking the second straight day of gains as investors priced in an 80 percent chance of a rate hike in December, according to the CME Group’s FedWatch tool.

At 9:44 a.m. ET the Dow Jones Industrial Average .DJI was down 69.44 points, or 0.38 percent, at 18,259.6.

The S&P 500 .SPX was down 8.75 points, or 0.4 percent, at 2,154.91 and the Nasdaq Composite.IXIC was down 15.58 points, or 0.29 percent, at 5,313.09.

All of the 11 major S&P 500 indexes were lower, with materials .SPLRCM dropping the most by 1.08 percent.

Apple (AAPL.O) rose 2.1 percent after rival Samsung said it would scrap its Galaxy Note 7 smartphones due to safety concerns.

St. Jude (STJ.N) dropped 3 percent in heavy premarket trading after the company warned that some of its implanted heart devices are at risk of premature battery depletion, a condition it said had been linked to two patient deaths.